I read Childhood's End back in high school. It probably could work as a miniseries, but 2001 and even V may have taken away some of it's potential visual impact.
Speaking of Arthur C. Clarke...
I wonder if they could bring Keir Dullea and Gary Lockwood back and digitally de-age them ala Jeff Bridges in Tron Legacy? Douglas Rain is still around, but doesn't seem to have done anything since 2007. Recasting Hal would be daunting.